mockforge_graphql/
handlers.rs

1//! GraphQL Handler System
2//!
3//! Provides a flexible handler-based system for GraphQL operations, similar to the WebSocket handler architecture.
4//! Handlers can intercept and customize query, mutation, and subscription resolution.
5
6use async_graphql::{Name, Request, Response, ServerError, Value, Variables};
7use async_trait::async_trait;
8use serde_json::json;
9use std::collections::HashMap;
10use std::sync::Arc;
11use thiserror::Error;
12
13/// Result type for handler operations
14pub type HandlerResult<T> = Result<T, HandlerError>;
15
16/// Errors that can occur during handler execution
17#[derive(Debug, Error)]
18pub enum HandlerError {
19    /// Error sending response
20    #[error("Send error: {0}")]
21    SendError(String),
22
23    /// JSON serialization/deserialization error
24    #[error("JSON error: {0}")]
25    JsonError(#[from] serde_json::Error),
26
27    /// Operation matching error
28    #[error("Operation error: {0}")]
29    OperationError(String),
30
31    /// Upstream passthrough error
32    #[error("Upstream error: {0}")]
33    UpstreamError(String),
34
35    /// Generic handler error
36    #[error("{0}")]
37    Generic(String),
38}
39
40/// Context for GraphQL handler execution
41pub struct GraphQLContext {
42    /// Operation name (query/mutation name)
43    pub operation_name: Option<String>,
44
45    /// Operation type (query, mutation, subscription)
46    pub operation_type: OperationType,
47
48    /// GraphQL query string
49    pub query: String,
50
51    /// Variables passed to the operation
52    pub variables: Variables,
53
54    /// Request metadata (headers, etc.)
55    pub metadata: HashMap<String, String>,
56
57    /// Custom data storage for handlers
58    pub data: HashMap<String, serde_json::Value>,
59}
60
61/// Type of GraphQL operation
62#[derive(Debug, Clone, PartialEq, Eq)]
63pub enum OperationType {
64    /// Query operation
65    Query,
66    /// Mutation operation
67    Mutation,
68    /// Subscription operation
69    Subscription,
70}
71
72impl GraphQLContext {
73    /// Create a new GraphQL context
74    pub fn new(
75        operation_name: Option<String>,
76        operation_type: OperationType,
77        query: String,
78        variables: Variables,
79    ) -> Self {
80        Self {
81            operation_name,
82            operation_type,
83            query,
84            variables,
85            metadata: HashMap::new(),
86            data: HashMap::new(),
87        }
88    }
89
90    /// Get a variable value
91    pub fn get_variable(&self, name: &str) -> Option<&Value> {
92        self.variables.get(&Name::new(name))
93    }
94
95    /// Set custom data
96    pub fn set_data(&mut self, key: String, value: serde_json::Value) {
97        self.data.insert(key, value);
98    }
99
100    /// Get custom data
101    pub fn get_data(&self, key: &str) -> Option<&serde_json::Value> {
102        self.data.get(key)
103    }
104
105    /// Set metadata
106    pub fn set_metadata(&mut self, key: String, value: String) {
107        self.metadata.insert(key, value);
108    }
109
110    /// Get metadata
111    pub fn get_metadata(&self, key: &str) -> Option<&String> {
112        self.metadata.get(key)
113    }
114}
115
116/// Trait for handling GraphQL operations
117#[async_trait]
118pub trait GraphQLHandler: Send + Sync {
119    /// Called before query/mutation execution
120    /// Return None to proceed with default resolution, Some(Response) to override
121    async fn on_operation(&self, _ctx: &GraphQLContext) -> HandlerResult<Option<Response>> {
122        Ok(None)
123    }
124
125    /// Called after successful query/mutation execution
126    /// Allows modification of the response
127    async fn after_operation(
128        &self,
129        _ctx: &GraphQLContext,
130        response: Response,
131    ) -> HandlerResult<Response> {
132        Ok(response)
133    }
134
135    /// Called when an error occurs
136    async fn on_error(&self, _ctx: &GraphQLContext, error: String) -> HandlerResult<Response> {
137        let server_error = ServerError::new(error, None);
138        Ok(Response::from_errors(vec![server_error]))
139    }
140
141    /// Check if this handler should handle the given operation
142    fn handles_operation(
143        &self,
144        operation_name: Option<&str>,
145        _operation_type: &OperationType,
146    ) -> bool {
147        // Default: handle all operations
148        operation_name.is_some()
149    }
150
151    /// Priority of this handler (higher = executes first)
152    fn priority(&self) -> i32 {
153        0
154    }
155}
156
157/// Registry for managing GraphQL handlers
158pub struct HandlerRegistry {
159    handlers: Vec<Arc<dyn GraphQLHandler>>,
160    /// Upstream GraphQL server URL for passthrough
161    upstream_url: Option<String>,
162}
163
164impl HandlerRegistry {
165    /// Create a new handler registry
166    pub fn new() -> Self {
167        Self {
168            handlers: Vec::new(),
169            upstream_url: None,
170        }
171    }
172
173    /// Create a handler registry with upstream URL
174    pub fn with_upstream(upstream_url: Option<String>) -> Self {
175        Self {
176            handlers: Vec::new(),
177            upstream_url,
178        }
179    }
180
181    /// Register a handler
182    pub fn register<H: GraphQLHandler + 'static>(&mut self, handler: H) {
183        self.handlers.push(Arc::new(handler));
184        // Sort by priority (highest first)
185        self.handlers.sort_by(|a, b| b.priority().cmp(&a.priority()));
186    }
187
188    /// Get handlers for a specific operation
189    pub fn get_handlers(
190        &self,
191        operation_name: Option<&str>,
192        operation_type: &OperationType,
193    ) -> Vec<Arc<dyn GraphQLHandler>> {
194        self.handlers
195            .iter()
196            .filter(|h| h.handles_operation(operation_name, operation_type))
197            .cloned()
198            .collect()
199    }
200
201    /// Execute handlers for an operation
202    pub async fn execute_operation(&self, ctx: &GraphQLContext) -> HandlerResult<Option<Response>> {
203        let handlers = self.get_handlers(ctx.operation_name.as_deref(), &ctx.operation_type);
204
205        for handler in handlers {
206            if let Some(response) = handler.on_operation(ctx).await? {
207                return Ok(Some(response));
208            }
209        }
210
211        Ok(None)
212    }
213
214    /// Execute after_operation hooks
215    pub async fn after_operation(
216        &self,
217        ctx: &GraphQLContext,
218        mut response: Response,
219    ) -> HandlerResult<Response> {
220        let handlers = self.get_handlers(ctx.operation_name.as_deref(), &ctx.operation_type);
221
222        for handler in handlers {
223            response = handler.after_operation(ctx, response).await?;
224        }
225
226        Ok(response)
227    }
228
229    /// Passthrough request to upstream server
230    pub async fn passthrough(&self, request: &Request) -> HandlerResult<Response> {
231        let upstream = self
232            .upstream_url
233            .as_ref()
234            .ok_or_else(|| HandlerError::UpstreamError("No upstream URL configured".to_string()))?;
235
236        let client = reqwest::Client::new();
237        let body = json!({
238            "query": request.query.clone(),
239            "variables": request.variables.clone(),
240            "operationName": request.operation_name.clone(),
241        });
242
243        let resp = client
244            .post(upstream)
245            .json(&body)
246            .send()
247            .await
248            .map_err(|e| HandlerError::UpstreamError(e.to_string()))?;
249
250        let response_data: serde_json::Value =
251            resp.json().await.map_err(|e| HandlerError::UpstreamError(e.to_string()))?;
252
253        // Convert JSON response to GraphQL Response
254        // Extract data and errors from the GraphQL response
255        let has_errors = response_data.get("errors").is_some();
256
257        // For now, return a null response with error status if there are errors
258        // In a full implementation, you would properly convert the JSON response to GraphQL types
259        if has_errors {
260            let error_msg = response_data
261                .get("errors")
262                .and_then(|e| e.as_array())
263                .and_then(|arr| arr.first())
264                .and_then(|e| e.get("message"))
265                .and_then(|m| m.as_str())
266                .unwrap_or("Upstream GraphQL error");
267
268            let server_error = async_graphql::ServerError::new(error_msg.to_string(), None);
269            Ok(Response::from_errors(vec![server_error]))
270        } else {
271            // Return successful response
272            // Note: Proper implementation would convert serde_json::Value to async_graphql::Value
273            Ok(Response::new(Value::Null))
274        }
275    }
276
277    /// Get upstream URL
278    pub fn upstream_url(&self) -> Option<&str> {
279        self.upstream_url.as_deref()
280    }
281}
282
283impl Default for HandlerRegistry {
284    fn default() -> Self {
285        Self::new()
286    }
287}
288
289/// Variable matcher for filtering operations by variable values
290#[derive(Debug, Clone)]
291pub struct VariableMatcher {
292    patterns: HashMap<String, VariablePattern>,
293}
294
295impl VariableMatcher {
296    /// Create a new variable matcher
297    pub fn new() -> Self {
298        Self {
299            patterns: HashMap::new(),
300        }
301    }
302
303    /// Add a pattern for a variable
304    pub fn with_pattern(mut self, name: String, pattern: VariablePattern) -> Self {
305        self.patterns.insert(name, pattern);
306        self
307    }
308
309    /// Check if variables match the patterns
310    pub fn matches(&self, variables: &Variables) -> bool {
311        for (name, pattern) in &self.patterns {
312            if !pattern.matches(variables.get(&Name::new(name))) {
313                return false;
314            }
315        }
316        true
317    }
318}
319
320impl Default for VariableMatcher {
321    fn default() -> Self {
322        Self::new()
323    }
324}
325
326/// Pattern for matching variable values
327#[derive(Debug, Clone)]
328pub enum VariablePattern {
329    /// Exact value match
330    Exact(Value),
331    /// Regular expression match (for strings)
332    Regex(String),
333    /// Any value (always matches)
334    Any,
335    /// Value must be present
336    Present,
337    /// Value must be null or absent
338    Null,
339}
340
341impl VariablePattern {
342    /// Check if a value matches this pattern
343    pub fn matches(&self, value: Option<&Value>) -> bool {
344        match (self, value) {
345            (VariablePattern::Any, _) => true,
346            (VariablePattern::Present, Some(_)) => true,
347            (VariablePattern::Present, None) => false,
348            (VariablePattern::Null, None) | (VariablePattern::Null, Some(Value::Null)) => true,
349            (VariablePattern::Null, Some(_)) => false,
350            (VariablePattern::Exact(expected), Some(actual)) => expected == actual,
351            (VariablePattern::Exact(_), None) => false,
352            (VariablePattern::Regex(pattern), Some(Value::String(s))) => {
353                regex::Regex::new(pattern).ok().map(|re| re.is_match(s)).unwrap_or(false)
354            }
355            (VariablePattern::Regex(_), _) => false,
356        }
357    }
358}
359
360#[cfg(test)]
361mod tests {
362    use super::*;
363
364    struct TestHandler {
365        operation_name: String,
366    }
367
368    #[async_trait]
369    impl GraphQLHandler for TestHandler {
370        async fn on_operation(&self, ctx: &GraphQLContext) -> HandlerResult<Option<Response>> {
371            if ctx.operation_name.as_deref() == Some(&self.operation_name) {
372                // Return a simple null response for testing
373                Ok(Some(Response::new(Value::Null)))
374            } else {
375                Ok(None)
376            }
377        }
378
379        fn handles_operation(&self, operation_name: Option<&str>, _: &OperationType) -> bool {
380            operation_name == Some(&self.operation_name)
381        }
382    }
383
384    #[tokio::test]
385    async fn test_handler_registry_new() {
386        let registry = HandlerRegistry::new();
387        assert_eq!(registry.handlers.len(), 0);
388        assert!(registry.upstream_url.is_none());
389    }
390
391    #[tokio::test]
392    async fn test_handler_registry_with_upstream() {
393        let registry =
394            HandlerRegistry::with_upstream(Some("http://example.com/graphql".to_string()));
395        assert_eq!(registry.upstream_url(), Some("http://example.com/graphql"));
396    }
397
398    #[tokio::test]
399    async fn test_handler_registry_register() {
400        let mut registry = HandlerRegistry::new();
401        let handler = TestHandler {
402            operation_name: "getUser".to_string(),
403        };
404        registry.register(handler);
405        assert_eq!(registry.handlers.len(), 1);
406    }
407
408    #[tokio::test]
409    async fn test_handler_execution() {
410        let mut registry = HandlerRegistry::new();
411        registry.register(TestHandler {
412            operation_name: "getUser".to_string(),
413        });
414
415        let ctx = GraphQLContext::new(
416            Some("getUser".to_string()),
417            OperationType::Query,
418            "query { user { id } }".to_string(),
419            Variables::default(),
420        );
421
422        let result = registry.execute_operation(&ctx).await;
423        assert!(result.is_ok());
424        assert!(result.unwrap().is_some());
425    }
426
427    #[test]
428    fn test_variable_matcher_any() {
429        let matcher = VariableMatcher::new().with_pattern("id".to_string(), VariablePattern::Any);
430
431        let mut vars = Variables::default();
432        vars.insert(Name::new("id"), Value::String("123".to_string()));
433
434        assert!(matcher.matches(&vars));
435    }
436
437    #[test]
438    fn test_variable_matcher_exact() {
439        let matcher = VariableMatcher::new().with_pattern(
440            "id".to_string(),
441            VariablePattern::Exact(Value::String("123".to_string())),
442        );
443
444        let mut vars = Variables::default();
445        vars.insert(Name::new("id"), Value::String("123".to_string()));
446
447        assert!(matcher.matches(&vars));
448
449        let mut vars2 = Variables::default();
450        vars2.insert(Name::new("id"), Value::String("456".to_string()));
451
452        assert!(!matcher.matches(&vars2));
453    }
454
455    #[test]
456    fn test_variable_pattern_present() {
457        assert!(VariablePattern::Present.matches(Some(&Value::String("test".to_string()))));
458        assert!(!VariablePattern::Present.matches(None));
459    }
460
461    #[test]
462    fn test_variable_pattern_null() {
463        assert!(VariablePattern::Null.matches(None));
464        assert!(VariablePattern::Null.matches(Some(&Value::Null)));
465        assert!(!VariablePattern::Null.matches(Some(&Value::String("test".to_string()))));
466    }
467
468    #[test]
469    fn test_graphql_context_new() {
470        let ctx = GraphQLContext::new(
471            Some("getUser".to_string()),
472            OperationType::Query,
473            "query { user { id } }".to_string(),
474            Variables::default(),
475        );
476
477        assert_eq!(ctx.operation_name, Some("getUser".to_string()));
478        assert_eq!(ctx.operation_type, OperationType::Query);
479    }
480
481    #[test]
482    fn test_graphql_context_metadata() {
483        let mut ctx = GraphQLContext::new(
484            Some("getUser".to_string()),
485            OperationType::Query,
486            "query { user { id } }".to_string(),
487            Variables::default(),
488        );
489
490        ctx.set_metadata("Authorization".to_string(), "Bearer token".to_string());
491        assert_eq!(ctx.get_metadata("Authorization"), Some(&"Bearer token".to_string()));
492    }
493
494    #[test]
495    fn test_graphql_context_data() {
496        let mut ctx = GraphQLContext::new(
497            Some("getUser".to_string()),
498            OperationType::Query,
499            "query { user { id } }".to_string(),
500            Variables::default(),
501        );
502
503        ctx.set_data("custom_key".to_string(), json!({"test": "value"}));
504        assert_eq!(ctx.get_data("custom_key"), Some(&json!({"test": "value"})));
505    }
506}
mockforge_graphql/handlers.rs

mockforge_graphql/
handlers.rs
